Vee notch weir level control system

ABSTRACT

IN THE ILLUSTRATED EMBODIMENT THE LEVEL OF A PLATING SOLUTION IS ADJUSTABLY DETERMINED BY METERING FLOW TO THE PLATING TANK WITH A VALVE EQUIPPED WITH A MICROMETER SCALE INDICATING THE VALVE ORIFICE AREA OPENING AND PROVIDIN G FOR THE CONTINUOUS OVERFLOW FROM THE PLATING TANK THROUGH A V NOTCH WEIR. OBSERVED MICROMETER READINGS ON THE METERING VALVE WILL PRODUCE CORRESPONDING PRECISE AND PREDICTABLE LEVELS OF THE PLATING SOLUTION OVER THE HEIGHT OF THE V NOTCH.

United States Patent Ryerson et al.

1 1] 3,763,028 1 Oct. 2, 1 973 VEE NOTCH WEIR LEVEL CONTROL 2,891,5746/1959 Dahlberg 137 577 SYSTEM 3,480,025 11/1969 Hsu et al l37/5632,962,427 "/1960 Kosowsky 204/237 [75] Inventors: James N.Ryerson,0eeanport; 3,168,457 2/1965 Grazen 204/237 Theodore R. Wall,Elizabeth, both 3,259,557 7/1966 Smith ct all 204/237 fN J 3,296,! 141/1967 Lloyd 204/237 [73] Assignee: a," gf g Corporation PrimaryExaminer-Winston A. Douglas amen Assistant Examiner-C. F. LefevourFiled: July 19, 196 Attorney-Hill, Sherman, Meroni, Gross & Simpson [21]Appl. No.: 654,436

[57] ABSTRACT [52] U.S. Cl. 204/237 In the illustrated m ment the levelf a plating so- [51] Int. Cl 801k 3/00 lutlon is ju tably determined bymetering flow to the [58] Field of Search 204/237, 238, 239, p ng tank ha v l eq ipped with a micrometer 204/232, 233, 234, 235, 236; l37/563,577 scale indicating the valve orifice area opening and pro- 1 vidingfor the continuous overflow from the plating [56] References Cited tankthrough a V notchweir. Observed micrometer UNITED STATES PATENTSreadings on the metering valve will produce corre- 2 590 538 3/1952 Huck37/563 sponding precise and predictable levels of the plating 2:690:76410/1954 Hoffmann. 137/563 over the v 2,743,909 5/1956 Lawlor 137/563 8Chims, 3 Drawing Figures 2 i a x Q it I I l I 1 '1 "H1 l 1 l'* *7 illr'- --l--. l--

I I 22 j! "53 .14 15 w l 1 i 35 Z6 27 U 3 .5 i 2.9 1 writ IE f5 PATENTED2 I975 IN VEN TORS James AZ 12396225022 7%0Q02 6/E W22 5) E $24ATTORNEYS VEE NOTCI-I WEIR LEVEL CONTROL SYSTEM BACKGROUND OF THEINVENTION In the plating art, and particularly in the plating ofelectrical components with precious metals, there is a great need forprecision control and adjustment of the level of the plating solution.In certain applications the parts to be plated are conveyed across theplating solution, and if the level of the plating solution is notcontinuously controlled with great precision, either the parts are onlypartially plated or the parts are plated to a greater height thanfunctionally necessary. With insufficient plating height, the part wouldnot meet requirements, while with excess plating height precious platingmaterial is wasted creating an economic loss which may be of substantialcommercial significance. Further excess plating height may cause anactual deterioration in performance of electrical components and thelike, even where the waste of material is not a substantial factor.

SUMMARY OF THE INVENTION It is therefore an object of the invention toprovide a precisely adjustable system for controlling liquid level in aplating tank or the like.

Another object of the invention is to provide such a system having aprecision and repeatability of adjustment substantially exceeding thatavailable in prior art systems of comparable cost and simplicity.

A further object of the invention is to provide such a system wherein asingle adjustment is required and wherein a visual indication is givenwhich may be reliably correlated with a desired liquid level.

Other objects, features and advantages of the present invention will beapparent from the following detailed description taken in connectionwith the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a somewhat diagrammaticillustration of an overall liquid level control system in accordancewith the present invention;

FIG. 2 is a somewhat diagrammatic vertical sectional view takengenerally along the line 11-11 of FIG. I; and

FIG. 3 is a diagrammatic top plan view of the system of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT A generally rectangular platingtank is genera indicated at having an interior wall 11 serving as a weirwith an outlet means 12 in the form of a V-shaped notch. While theplating tank may have any desired configuration, it is diagrammaticallyindicated as having a front wall 14, side walls 15 and 16, a rear wall17 and a bottom wall 18. For the sake of diagrammatic illustration, itmay be assumed that overflow compartment 20 is defined by weir 1 l, acentral portion of front wall 14, and connecting wall portions 22 and23. A chamber for receiving the plating solution is that portion of theplating tank 10 excluding the overflow compartment 20. An exemplarylevel for the plating solution in the chamber is indicated by thereference numetal 25 in FIG. 2.

In the illustrated embodiment, a sump tank is indicated at 26 having aminimum liquid level such as indicated at 27 and provided with acirculation pump as indicated at 29 for supplying the plating liquidfrom the tank 26 to the plating tank 10. The input line to the platingtank is indicated diagrammatically at 30 and a micrometer indicatingmetering valve is indicated at 32 for adjustably determining the rate offlow of the plating liquid to the tank 16. The metering valve 32 isequipped with a micrometer scale indicating the valve orifice areaopening and is manually adjustable by means diagrammatically indicatedat 33. The system is so constructed that there is a continuous flow ofthe plating liquid into the chamber of plating tank 16 via input line 30with liquid in the plating tank continuously flowing through the V notch12 and into the overflow compartment 20 from which liquid returns viareturn line 35 to the sump 26.

The capacity of the pump 29 is such that with the metering valve 32fully open, the level 25 in the plating tank 10 will be maintained atthe full overflow capacity of the V notch 12, that is at leastsubstantially at the level of the top surface 37 of weir 11. By reducingthe orifice area of the metering valve 32, the flow rate is reduceduntil the level such as indicated at 25 of the plating solution is onlyslightly above the lowermost point such as indicated at 38 of V notch12. Thus,-the range of adjustment of the metering valve 32 correspondsto a range of plating solution levels over the effective height of the Vnotch 12. Over this operating range, there is a continuous overflow ofplating solution through the V notch 12 and into the overflowcompartment 20.

Observed micrometer readings on the metering valve 32 will produceprecise and predictable levels such as indicated at 25 in the platingtank for the range of plating solution levels corresponding to theheight of the V notch 12.

Thus, if for a given type of workpiece to be plated, the workpiece is tobe moved through the plating solution at a predetermined level relativeto the upper edge of the plating tank 10, then the setting of the manualadjustment means 33 of the metering valve 32 which provides the desiredlevel of the plating solution can be noted, and the metering valve 32reset to this value on the micrometer scale whenever the particularworkpiece is to be plated. Further, the level of the plating solutionrelative to the top edge of the tank 10, for example, may be determinedfor various settings of the metering valve 32, and thereafter a reliableprecisely predictable level of the plating solution may be selectedsimply by setting of the metering valve 32 to the correspondingmicrometer reading. This feature of the illustrated system greatlyfacilitates the adjustment of plating equipment to handle differenttypes of workpieces and the like in quick succession.

To place the system in operation, with the working chamber 39 of theplating tank. filled to a level at the bottom point 38 of the V notch 12and with the sump 26 filled to capacity, the circulation pump 29 isstarted. Liquid pumped from the sump tank 26 up to the plating tank 16is metered by the micrometer indicating metering valve 32. The liquidlevel rise produced in the plating tank overflows through the V notch 12into the overflow compartment 20, FIG. 2, and returns by gravity throughreturn line 35 to the sump. The liquid level produced in the platingtank is a function of the orifice opening in the metering valve ;32versus the overflow capacity of the V notch 12. As previously stated,with the valve 32 fully open, the capacity of pump 29 is such as toproduce a level in the plating tank equal to the full overflow capacityof the V notch, this level being indicated at 37 in FIG. 1. Observedmicrometer readings on the metering valve 32 will produce precise andpredictable levels in the plating tank, adjustable through the depth ofthe V notch 12.

It will be noted that the V-shaped notch provides a generally triangularcross section liquid flow path which flow path has a more than linearincrease in flow area as a function of increasing liquid level in theworking chamber 39 of the plating tank. More specifically, the flow areaprovided by the notch 12 increases approximately as the square of theheight of the plating bath above the bottom of the notch.

Further details of construction and operation of the plating tank andthe plating system to which the present invention applies are found inthe copending applications Ryerson et al US. Ser. 310,274 filed Sept.20, 1963 and Ryerson et al U.S. Ser. 433,029 filed Feb. 16, 1965, andthe disclosures of both these applications are incorporated herein byreference in their entireties. These applications specifically disclosea plating system wherein different types of work units are to betransported at different times across the plating bath at apredetermined level with portions of the work units immersed in theplating bath for the purpose of being plated over respectivepredetermined extents thereof. Utilizing the features of the presentinvention, as the plating system is adjusted to work units requiringdifferent plating bath levels, the metering valve 32 is set tocorresponding predetermined settings as determined from the micrometerscale thereof, thus simplifying and expediting the changeover of thesystem to different types of work units.

It will be apparent that many modifications and variations may beeffected without departing from the scope of the novel concepts of thepresent invention.

I claim as my invention:

1. A plating chamber with a liquid level control system comprising atank having a working chamber for containing a liquid,

an input line for supplying liquid to said working chamber, said chamberhaving a weir with a fixed area, generally V-shaped notched outlet meansfor controlling discharge of liquid from said chamber,

a sump tank constructed to receive liquid from the working chamber,

a pump connected to the sump tank and having an output operable tosupply liquid under pressure at said output for delivery to the workingchamber of 50 said metering valve.

said tank,

flow control means comprising a micrometer indicating, metering valvebetween the pump output and the tank input for metering the flow ofliquid to the working chamber of said tank,

said weir outlet means being shaped to provide a more than linearincrease in flow area as the function of increasing liquid level in theworking chamber of said tank,

the relation between the capacity of said pump, the

metering valve and said weir outlet means being such as to provide apredictable change in liquid level in said chamber at different settingsof said metering valve and to maintain a substantially constant level insaid chamber at each different setting of said valve during continuouscirculation of liquid to and from said chamber.

2. The system of claim 1 with said weir outlet means providing agenerally square law increase in flow area as a function of increasingliquid level in the working chamber of said tank.

3. The system of claim with said tank containing a plating liquid andhaving means for plating said material on workpieces partially immersedin said plating liquid, and said weir outlet means providing asubstantially square law increase in flow area as a function of thelevel of said plating liquid in said working chamber.

4. The system of claim 1 with said flow control means comprising anadjustable metering valve providing for adjustment of the flow area ofsaid valve and having a micrometer scale indicating said setting.

5. The system of claim 3 with said flow control means comprising anadjustable metering valve providing a micrometer adjustment of the flowarea of said valve.

6. The system of claim 1 with said weir outlet means comprising a Vshaped notch, and said flow control means comprising an adjustablemetering valve providing a micrometer adjustment of flow area.

7. The system of claim 3 with said weir outlet means comprising aV-shaped notch and said flow control means comprising an adjustablemetering valve providing a micrometer adjustment of the flow area ofsaid valve.

8. The system of claim 7 in which the relation between said pumpcapacity and said weir outlet area is such as to maintain the level ofsaid plating bath near the top of said V-shaped notch with saidmicrometer valve fully open and being operative to maintain the level ofsaid plating path near the bottom of said V- shaped notch with a minimumorifice adjustment of

